Negative pressure

Negative pressure is misunderstood as pressure less than that of the ambient atmosphere. Actually what they mean is that there is a pressure difference between a region of high pressure and an other region of low pressure. A room with a lower pressure than its surroundings will cause air to flow into the room from the outside whenever a door or window is opened. It is often used in a hospital setting to quarantine people afflicted with highly contagious, deadly, airborne diseases.

Related Topics:
Negative pressure - Hospital - Quarantine - Diseases

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Large pressure differences are also often found in sub-sea pipelines where the depth of water produces such a high external pressure that any leak would actually be from the sea water into the pipeline. Which is a good way of avoiding oilspills.

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Negative pressure is the opposite of positive pressure. But pressure is due to the force that pushes in on all sides when an object is submerged in a fluid (liquid or gas). That external pressure would drop to zero in a complete vacuum. So negative pressure would then actually mean that there is an outward pull on an object when it is surrounded by some other rather odd material. This makes for great science fiction but not science fact.

Related Topics:
Positive pressure - Pressure

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